1. Field of the Invention
The present invention relates to a valve timing adjusting device in which an open-close timing of a suction (or intake) valve or an exhaust valve of an engine is changed according to operation conditions of the engine.
2. Description of Related Art
A prior-art example of a vane type valve timing adjusting device is disclosed in the Published Unexamined Japanese Patent Application H9-303118 (1997). In this valve timing adjusting device, a cam shaft is driven with a timing pulley or a chain sprocket which is rotated in synchronization with the rotation of a crank shaft of an engine, and a suction valve or an exhaust valve is opened or closed according to a phase difference based on a rotational movement of the cam shaft relative to the timing pulley or the chain sprocket.
FIG. 1 to FIG. 3 are drawings respectively showing a vane type conventional valve timing adjusting device. FIG. 1 is a vertical sectional view of the valve timing adjusting device, and FIG. 2 and FIG. 3 are respectively sectional views taken substantially along line Axe2x80x94A of FIG. 1. FIG. 2 shows the valve timing adjusting device set in a position condition in which a cam shaft is placed at a maximally spark-lag (or timing-retarded) position in phase with respect to the rotation of a timing pulley, and FIG. 3 shows the valve timing adjusting device set in a position condition in which a cam shaft is placed at a maximally spark-advance (or timing-advance) position in phase with respect to the rotation of a timing pulley. In FIG. 1, 1 indicates a valve timing adjusting device. 2 indicates a cam shaft for a suction valve. The cam shaft 2 is rotatably supported by a cylinder head (not shown). As shown in FIG. 1, a timing pulley 3 is arranged on a top portion of the cam shaft 2 to receive a rotational force of a crank shaft (not shown) of an engine through a belt or chain. An external rotor 5 is integrally fixed to the timing pulley 3 by using a plurality of bolts 4 to prevent a rotational movement of the timing pulley 3 relative to the external rotor 5. A cover 6 is fixed to one end of the external rotor 5 by using the bolts 4. In an internal opening of the external rotor 5, an internal rotor 7 is arranged. A length of the internal rotor 7 in an axial direction of the cam shaft 2 is almost equal to that of the external rotor 5. The internal rotor 7 is integrally fitted to the top portion of the cam shaft 2 by a bolt 9 so as to place the timing pulley 3 between a protruding portion 8 of the cam shaft 2 and the internal rotor 7. In the inside of the cam shaft 2, a spark-advance oil passage 10 and a spark-lag oil passage 11 are formed by drilling work so as to extend in the axial direction of the cam shaft 2. The spark-advance oil passage 10 and the spark-lag oil passage 11 lead to an oil supply source (not shown) through an oil supply channel 12 and an oil discharge channel 13 which are arranged in a cylinder head (not shown).
As shown in FIG. 2 and FIG. 3, on the inner circumferential side of the external rotor 5, five pressure chambers 15 and a supporting hole 16 are formed. The five pressure chambers 15 are partitioned by a plurality of portioning walls (or a plurality of shoes) 14 of the external rotor 5, and the supporting hole 16 extends in a radial direction of the external rotor 5. A leading hole 17 is arranged in near to the center of the bottom of the supporting hole 16, and a diameter of the leading hole 17 is smaller than that of the supporting hole 16. A slide pin 18 is inserted into the leading hole 17. A slide pin supporting portion 19 is integrally formed with the slide pin 18 so as to be formed into the bottom portion of the slide pin 18. A ring member 20 is fixedly attached to the outer circumferential surface of the supporting hole 16, and a spring 21 is arranged in a position between the slide pin supporting portion 19 and the ring member 20 so as to press the slide pin 18 toward the inner circumferential side of the external rotor 5. Here, the ring member 20 is inserted into the supporting hole 16 with a fixed force or is screwed to the outer circumferential surface of the supporting hole 16 to be fixed in the supporting hole 16. Therefore, the ring member 20 functions as a supporting seat to fix one end of the spring 21 at a prescribed position.
On the outer circumferential surface of the inner rotor 7, five vanes 22 are fitted to the inner rotor 7 so as to be placed in the five pressure chambers 15 respectively. Each vane 22 can be rotated in a circle-circumferential direction of the cam shaft 2 in the corresponding pressure chamber 15, and the vanes 22 divide the five pressure chambers 15 into a group of spark-advance hydraulic oil chambers 23, 24, 25, 26 and 27 and a group of spark-lag hydraulic oil chambers 28, 29, 30, 31 and 32. An oil pressure in each spark-advance hydraulic oil chamber 23, 24, 25, 26 or 27 is adjusted by oil supplied or discharged through the spark-advance oil passage 10 and a spark-advance oil passage 33, 34, 35, 36 or 37. Also, an oil pressure in each spark-lag hydraulic oil chamber 28, 29, 30, 31 or 32 is adjusted by oil supplied or discharged through the spark-lag oil passage 11 and a spark-lag oil passage 38, 39, 40, 41 or 42. 43 indicates a receiving hole. arranged in the internal rotor 7. The slide pin 18 can be inserted into the receiving hole 43. 44 indicates an oil passage leading to the receiving hole 43. The oil passage 44 leads to the spark-advance oil passage 10 and the spark-advance oil passages 33, 34, 35, 36 and 37.
Next, an operation is described.
In the position condition shown in FIG. 2, the cam shaft 2 is placed at a maximally spark-lag position with respect to the rotation direction of the timing pulley 3 shown by an arrow of FIG. 2. When the timing pulley 3 is rotated with a crank shaft (not shown), the rotational-force of the timing pulley 3 is transmitted to the cam shaft 2, which can not rotate relative to the timing pulley 3, through the slide pin 18, and the cam shaft 2 is rotated in the rotation direction indicated by the arrow of FIG. 2.
Here, the phase of each vane 22 can be changed in the rotation direction of the cam shaft 2, and information relating to a rotation frequency in an engine and a driving power of the engine is sent to a control circuit (not shown). Therefore, in cases where it is judged in the control circuit that the advance of the cam shaft 2 in phase with respect, to the rotation of the timing pulley 3 is preferred, oil is supplied to the spark-advance oil passage 10, oil of the spark-lag oil passage 11 is discharged, and the phase of the cam shaft 2 with respect to the timing pulley 3 is changed. More precisely, a control valve (not shown) leading to both the oil supply channel 12 and the oil. discharge channel 13 is controlled so as to supply oil to the spark-advance oil passage 10. The oil supplied to the spark-advance oil passage 10 flows into the oil passage 44, and the oil pushes the top portion of the slide pin 18 against the resilient force of the spring 21. In the position condition shown in FIG. 2, the top end of the spark-advance oil passage 33 does not lead to the spark-advance hydraulic oil chamber 23, and the top end of the spark-advance oil passage 37 does not lead to the spark-advance hydraulic oil chamber 27. Therefore, the oil pressure in the oil passage 44 is necessarily increased by the oil which is supplied from the spark-advance oil passages 34, 35 and 36 to the spark-advance hydraulic oil chambers 24, 25 and 26 respectively, the slide pin 18 is pushed out from the receiving hole 43, and each vane 22 moved with the cam shaft 2 is rotated in the rotation direction indicated by the arrow of FIG. 2. When the cam shaft 2 is rotated by a prescribed angle, the top ends of the spark-advance oil passages 33 and 37 lead to the spark-advance hydraulic oil chambers 23 and 27, and the oil is supplied to the spark-advance hydraulic oil chambers 23 and 27. In contrast, the oil placed in the spark-lag hydraulic oil chambers 28, 29, 30, 31 and 32 is discharged through the spark-lag oil passages 38, 39, 40, 41 and 42 and the spark-lag oil passage 11. Therefore, each vane 22 is rotated and moved to the maximally spark-advance position shown in FIG. 3 by using an oil pressure difference between both hydraulic oil chambers placed on the both sides of the vane 22. Thus the cam shaft 2 is advanced in phase with respect to the rotation of the timing pulley 3.
In contrast, in cases where it is desired to move the cam shaft 2 to a spark-lag position in phase with respect to the rotation of the timing pulley 3, oil is supplied in an opposite direction to move each vane 22 placed in the maximally spark-advance position shown in FIG. 3 to the maximally spark-lag position shown in FIG. 2. In detail, the control valve (not shown) is controlled so as to supply oil from the spark-lag oil passage 11 to the spark-lag hydraulic oil chambers 28, 29, 30, 31 and 32 through the spark-lag oil passages 38, 39, 40, 41 or 42, and the oil placed in the spark-advance hydraulic oil chambers 23, 24, 25, 26 and 27 is discharged through the spark-advance oil passages 33, 34, 35, 36 and 37 and the spark-advance oil passage 10. Therefore, each vane 22 is rotated and moved to the maximally spark-lag position shown in FIG. 2 by using an oil pressure difference between both hydraulic oil chambers placed on the both sides of the vane 22. In this position condition, when the timing pulley 3 is rotated, the slide pin 18, which is pushed by the spring 21 toward the cam shaft 2, is inserted into the receiving hole 43, and rotation of the cam shaft 2 relative to the timing pulley 3 is prevented.
However, in the conventional valve timing adjusting device, the ring member 20 is inserted into the supporting hole 16 with a fixed force or is screwed to the outer circumferential surface of the supporting hole 16 to be fixed in the supporting hole 16. Therefore, for example, the fitting of the ring member 20 to the outer circumferential surface of the supporting hole. 16 may easily become loosened because of a failure in the press fitting of the ring member 20. Otherwise the fitting of the ring member 20 may easily become loosened because of both a temperature change and a difference in a coefficient of linear thermal expansion between the ring member 20 and the external rotor 5, or the screwed connection of the ring member 20 with the outer circumferential surface of the supporting hole 16 is easily loosened because of vibration. As a result, the position of the ring member 20 is shifted, and the spring 21, which gives the resilient force toward a shaft center of the valve timing adjusting device, is set to an unnecessarily prolonged length. Therefore, the resilient force of the spring 21 is lowered, and there is probability that the slide pin 18 comes out from the receiving hole 43. In this case, even though it is required to prevent the rotational motion of the inner rotor 7 relative to the external rotor 5, there is probability that the prevention of the rotational motion of the inner rotor 7 relative to the external rotor 5 is impossible. Also, in extreme cases, there is probability that the ring member 20 comes out from the supporting hole 16. In this case, there is probability that complete failure is caused in the valve timing adjusting device.
An object of the present invention is to provide, with due consideration to the drawbacks of the conventional valve timing adjusting device, a valve timing adjusting device in which a preventing means for preventing a position change in a holding means such as the ring member 20 is arranged to ensure prevention of detachment of the holding means and to ensure prevention of a position change of the holding means. The preventing means functions as a relative rotational motion preventing means to reliably prevent rotational motion of the inner rotor 7 relative to the external rotor 5 and to reliably remove the prevention of the relative rotational motion.
A valve timing adjusting device according to the present invention comprises a first rotation member which has a plurality of shoes and is arranged so as to be rotatable around a cam shaft, a second rotation member which has a plurality of vanes, is arranged in an internal hole of the first rotation member, is arranged to allow rotational motion relative to the first rotation member within a prescribed angle range and is fixed to the cam shaft, a spark-lag hydraulic oil chamber and a spark-advance hydraulic oil chamber which are respectively arranged between each vane of the second rotation member and the corresponding shoe of the first rotation member, and a lock mechanism for preventing the rotational motion of the second rotation member relative to the-first rotation member while being operated along a radial direction of the first rotation member. The lock mechanism comprises a restricting means, which is movable in the radial direction of the first rotation member, for restricting the rotational motion of the second rotation member relative to the first rotation member on condition that the prevention of the rotational motion of the second rotation member relative to the first rotation member is removable, a receiving hole, which is arranged on an outer circumferential surface of the second rotation member, for receiving the restricting means, a force giving means forgiving the restricting means a force which is directed inwardly along the radial direction of the first rotation member, a holding means for positioning the force giving means, and a preventing means for preventing the holding means from being moved outwardly along the radial direction of the first rotation member. Therefore, the preventing. means can prevent the holding means from moving outwardly along the radial direction of the first rotation member. Also, the preventing means can prevent the force giving means from moving outwardly along the radial direction of the first rotation member. Therefore, the preventing means can prevent the restricting means from early detaching from the receiving hole when the rotational motion of the second rotation member relative to the first rotation member is prevented, the slide pin 18 can be reliably caught by a receiving hole 43 if necessary. Accordingly, the rotational motion of the second rotation member relative to the first rotation member can be reliably prevented.
Also, in the valve timing adjusting device according to the present invention, the preventing means, for example, using a knock pin is arranged in the first rotation member along an axial direction of the first rotation member, and a top end of the preventing means is caught by the holding means. In this case, because the preventing means is caught by the holding means, the holding means and the restricting means can be easily prevented from being moved outwardly along the radial direction of the first rotation member.
Also, in the valve timing adjusting device according to the present invention, the holding means has a smaller diameter portion at an outside position along the radial direction of the first rotation member, the holding means has an uneven portion composed of the smaller diameter portion and a larger diameter portion adjacent to the smaller diameter portion, a top portion of the preventing means is caught by the uneven portion. In this case, because the preventing means is caught by the uneven portion, the holding means and the restricting means can be easily, prevented from being moved outwardly along the radial direction of the first rotation member.
Also, in the valve timing adjusting device according to the present invention, one end of the preventing means, which penetrates through the first rotation member in an axial direction of the first rotation member, is supported to allow rotational motion of the preventing means relative to the cam shaft and is caught by a third rotation member, and the other end of the preventing means is caught by the holding means. In this case, when a positioning means for determining a relative position of the third rotation member to the first rotation member is used as the restricting means, the holding means and the restricting means can be easily prevented from being moved outwardly along the radial direction of the first rotation member.
Also, in the valve timing adjusting device according to the present invention, the first rotation member has both a receiving hole, which extends in the radial direction of the first rotation member and receives the holding means, and a circular shaped groove which is formed on an inner wall surface of the receiving hole, and the preventing means is formed of a nearly-annular member, of which a part is cut out, and can be tightly fitted in the circular shaped groove. In this case, because the preventing means, which is tightly fitted in the circular shaped groove of the first rotation member and is fixed to the first rotation member, can come in contact with the holding means, the holding means and the restricting means can be easily prevented from being moved outwardly along the radial direction of the first rotation member.
Also, in the valve timing adjusting device according to the present invention, the first rotation member has both a receiving hole, which extends in the radial direction of the first rotation member and receives the holding means, and a circular shaped groove which is formed on an inner wall surface of the receiving hole, the holding means has a protruding portion which protrudes outwardly along the radial direction of the first rotation member, and the preventing means is formed of a disk-shaped member which has both an outer end portion caught by the circular shaped groove of the first rotation member and a center opening from which the protruding portion of the holding means is received. In this case, the protruding portion of the holding means penetrates through the center opening of the restricting means, and the outer end portion of the preventing means is caught by the circular shaped groove of the first rotation member. Therefore, when the protruding portion of the holding means is pushed inwardly along the radial direction of the first rotation member while the deformation of the preventing means is maintained, the holding means is deformed and inserted into the preventing means, and the shape of the preventing means is returned to a nearly original shape. Therefore, the holding means and the restricting means can be easily prevented from being moved outwardly along the radial direction of the first rotation member.
Also, in the valve timing adjusting device according to the present invention, the preventing means is formed of an annular cover with which an outer circumferential surface of the first rotation member is covered, and an inner circumferential surface of the annular cover comes in contact, with the holding means. In this case, when the annular cover of the first rotation member is used as the preventing means, the holding means and the restricting means can be easily prevented from being moved outwardly along the radial direction of the first rotation member.
Also, in the valve timing adjusting device according to the present invention, the preventing means is formed of a skirt portion of an nearly-tubular cover member with which both the first rotation member and the second rotation member are covered, and an inner circumferential surface of the skirt portion of the nearly-tubular cover member comes in contact with the holding means. In this case, when the nearly-tubular cover member is used as the preventing means, the holding means and the restricting means can be easily prevented from being moved outwardly along the radial direction of the first rotation member.
Also, in the valve timing adjusting device according to the present invention, the first rotation member has a receiving hole which extends in the radial direction of the first rotation member and receives the holding means, and the preventing means comprises both a first screw portion, which is arranged on an outer circumferential surface of the holding means according to a rolling operation, and a second screw portion which is arranged on an inner circumferential surface of the receiving hole according to the rolling operation and is connected with the first screw portion. In this case, because the second screw portion is connected with the first screw portion, the holding means and the restricting means can be easily prevented from being moved outwardly along the radial direction of the first rotation member.
Also, in the valve timing adjusting device according to the present invention, the preventing means further comprises adhesive with which a space between the first screw portion and the second screw portion is coated. In this case, because a screw-connection plane between the first screw portion and the second screw portion is coated with the adhesive, the holding means and the restricting means can be easily prevented from being moved outwardly along the radial direction of the first rotation member.